Chemical mechanical polishing (CMP) is a process commonly used in the manufacture of high-density integrated circuits to planarize or polish a layer of material deposited on a substrate. A carrier head may provide the substrate retained therein to a polishing station of the CMP system and controllably urge the substrate against a moving polishing pad. CMP is effectively employed by providing contact between a feature side of the substrate and moving the substrate relative to the polishing pad while in the presence of a polishing fluid. Material is removed from the feature side of the substrate that is in contact with the polishing surface through a combination of chemical and mechanical activity. Particles removed from a substrate while polishing become suspended in the polishing fluid. The suspended particles are removed while polishing the substrate by the polishing fluid.
The carrier head typically includes a retaining ring that circumscribes the substrate and may facilitate holding of the substrate in the carrier head. A bottom surface of the retaining ring is typically made of a sacrificial plastic material that is generally in contact with the polishing pad during polishing. The sacrificial plastic material is designed to progressively wear over sequential runs.
The retaining rings are typically manufactured using conventional CNC machining methods. However, the surface of the sacrificial plastic material produced by conventional machining methods is typically too rough and must be conditioned to produce a smoother surface and an acceptable flatness. One method for “break in” conditioning of a new retaining ring involves installing the retaining ring on a fully functional CMP system and running a recipe with numerous dummy wafers. However, this approach is inefficient due to high capital and labor costs.
Therefore, there is a need for a simplified method and apparatus for producing retaining rings having a desired roughness and surface flatness.